title: Synthesis, structural analysis, and properties of [8]circulenes.
abstract: Polygons: [8]Circulenes were easily prepared by Pd-catalyzed annulations of tetraiodotetraphenylenes with alkynes. Their saddle-shaped structure with an [8]radialene character was identified by X-ray crystallography. Similar to 1,3,5,7-cyclooctatetraene, they have a tub-shaped eight-membered ring, but all of the bond lengths and bond angles are almost equal. Variable-temperature NMR investigations showed interesting dynamic behavior.
authors.affiliation: Department of Chemistry, National Cheng Kung University, No. 1 Ta-Hsueh Rd., 70101 Tainan, Taiwan.
authors.forename: Chieh-Ning
authors.initials: CN
authors.lastname: Feng
authors.forename: Ming-Yu
authors.initials: MY
authors.lastname: Kuo
authors.forename: Yao-Ting
authors.initials: YT
authors.lastname: Wu
keywords: [8]circulenes; alkynes; annulation; palladium; tetraphenylenes